Cellular networks have evolved from delivering robust voice services with 1st and 2nd generation standards towards generations of standards that enable data-centric networks and the proliferation of Smartphones with Wi-Fi and 3G/LTE capabilities. The resulting surge in data traffic volumes has led operators to recognize the opportunity offered by both Wi-Fi technology and unlicensed spectrum for traffic offload.

In response to operator need for integrated Wi-Fi offloading technologies in their networks, the 3rd Generation Partnership Project (3GPP) has defined various methods of LTE-WLAN interworking ranging from Non-Seamless WLAN Offload (NSWO) and loosely coupled methods such as S2b (later on enhanced with radio layer interworking capabilities), to LTE-WLAN Radio Level Integration, a more advanced RAN anchored solution with IPsec Tunnel (LWIP), to LTE-WLAN Aggregation (LWA), which allows operators to seamlessly integrate WLAN as a “new Radio Access Network (RAN)”, into their network.